Here is the location of all maps. Be sure to click on many of the small images to see the larger image (hosted elsewhere)–not all images indicate they are thumbnails.
Very interesting discussion of Alaska’s ecoregions is here. There used to be a related set of descriptions plus the detailed maps, but I can’t find the website at the moment.
“Ecological Subregions of the United States”
Alaska Ecoregions Mapping –
National Geologic Map Database http://ngmdb.usgs.gov/ngmdb/ngm_catalog.ora.html